Incandescent lamp



Feb. 24,1970 c, L, PETERSON 3,497,752

INCANDESCENT LAMP 3 Filed NOV. 6, 1967 CARL L. PETERSON INVENTOR ATTORNEY United States Patent 3,497,752 INCANDESCENT LAMP Carl L. Peterson, Gloucester, Mass., assignor to Sylvania Electric Products, Inc., a corporation of Delaware Filed Nov. 6, 1967, Ser. No. 680,893 Int. Cl. H01j 1/88, 19/42 US. Cl. 313-271 12 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention This invention pertains to incandescent lamps and particularly to tubular quartz halogen lamps in which a quantity of halogen regenerates a tungsten filament. More specifically, it pertains to the support of the filaments and lead-in wires of such lamps.

Description of the prior art Quartz halogen lamps have become increasingly useful in lighting applications because of their higher efficiency, better maintenance and smaller size in comparison to the prior art incandescent lamps. As a result of this commercial success, quartz halogen lamps are being developed with higher power ratings. These lamps :are necessarily larger and present some problems that are not usually encountered with lower wattage lamps. One problem involves a quartz to metal seal that can satisfactorily handle larger amounts of electric current. In a co-pending application, S. N. 596,908, Method of Sealing Quartz to Metal and Devices, filed on Nov. 25, 1966 by Paul E. Gates and David R. Dayton, and assigned to the instant assignee, a lamp is shown which has an improved seal capable of handling increased current.

Another problem concerns the adequacy of the support of the mount at the end opposite the lamp base, the seal of which is sometimes the only support for the mount. The increased sizes and lengths of the mounts of higher wattage lamps aggravate the problem of support.

For example, where a filament mount is greater than about one or two inches long and is only supported at the base of the lamp, the amplitude of oscillation of the unsupported end of the mount resulting from operational vibration can be great enough to severely reduce the useful life of the lamp. The life reduction can occur by a loosening of the electrical connection between the filament and lead-in wire, with subsequent arcing therebetween, or by a displacement of the filament from its efficient centralized position. Furthermore, excessive movement of the unsupported end of the mount can increase the stress on the quartz to metal seal at the base and cause premature failure of the seal. Physical shock of the lamp, such :as can occur during transportation or rough handling, can produce similar harmful results.

In addition, the corrosive effect of. the halogen atmosphere, especially at the high temperatures at which lamps of this type operate, severely limits the materials that can be used within the lamp envelope. Generally, only tungsten and quartz are suitable. The tungsten filament to 3,497,752 Patented Feb. 24, 1970 ice tungsten lead-in wire connection in the lower wattage lamps is usually a weld or hot crimp. But, mainly because of the increased wire sizes involved, these connections are not satisfactory in higher wattage lamps.

SUMMARY OF THE INVENTION This invention discloses a mount support which materially stabilizes the central positioning of the filament and lead-in wire throughout the life of the lamp and improves the electrical connection therebetween. A feature of this invention is a filament connector which includes a coil near its end. The coil encircles the lead-in wire and has two arms, one of which constitutes the filament leg. One arm overlaps the other in a compressive engagement, thereby constricting the coil in its direction of winding and clamping it on the lead-in wire. A hook at the end of the overlapping arm prevents the disengagement thereof.

A similar coil stabilizes the interior end of the lead-in wire and protects it against excessive movement from vibration and shock. In this coil, the two arms are tangential to the body of the coil, extend in opposite directions and press against the envelope wall. The resultant pressure constricts the coil in its direction of winding and clamps it on the lead-in wire, thereby supporting the lead-in wire against the envelope wall by means of the support coil.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a perspective view of a lamp in accordance with this invention.

FIGURE 2 is an enlarged perspective view of the coil at the end of the filament leg connected to the lead-in wire.

FIGURE 3 is an enlarged perspective view of the supporting coil on the lead-in wire pressing against the envelope wall.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGURE 1, envelope 1 is made of a heatresistant, light transmitting material, usually quartz, and generally has a tubular shape. Two refractory metal leadin wires 2 and 3, usually tungsten, are supported in cylindrical quartz to metal seals 4 at the base 10 of the lamp and extend into the interior of envelope 1. As is usual in single-ended lamps of this type, elongated tungsten filaments 5 are mounted on lead-in wires 2 and 3 longitudinally with respect to envelope 1 and, therefore, one lead-in wire, shown in the drawing as lead-in wire 2, is longer than the other. The interiorly extending portions of lead-in wires 2 and 3 have suitable bends to provide for a substantially centralized positioning of the filaments mounted thereon although, as shown here, an adequate space is maintained between the filaments 5 of a double filament lamp to prevent electrical shorting therebetween.

Filament 5 is connected, at each end, to filament connector 6, which comprises, as shown in FIGURE 2, coil body 7 and protruding arms 8 and 9, all formed from a single length of refractory metal wire, usually tungsten. Arm 8 also constitutes the leg of the filament and is conveniently attached to the end of filament 5. For example, where filament 5 is a coiled coil, the end of arm 8 is bent into a suitable curve and inserted into a sufficient number of primary turns at the end of filament 5 to establish a satisfactory physical and electrical connection therebetween. Arm 9 protrudes from coil body 7 in the same approximate direction as does arm 8 and, at least when connector 6 is initially formed, is spaced a short distance from arm 8. The short separation between arms 8 and 9 is in the direction of winding of coil body 7 so that, when arms 8 and 9 are squeezed together into contact, coil body 7 is constricted and reduced slightly in diameter. The inside diameter of coil body 7, when it is wound, is approximately equal to the diameter of lead-in wires 2 and 3 in order to permit coil body 7 to be slip fit onto the lead-in wire. However, after the assembly of coil bodies 7 on lead-in wires 2 and 3 with proper alignment of filaments 5 therebetween, arms 8 and 9 are squeezed together until the end of arm 9 overlaps and engages arm 8. Arm 9 is shorter than arm 8 and, therefore, the point of overlap is short of filament 5. In addition, the end of arm 9 is hook-shaped to prevent disengagement of arm 9 from arm 8. The engagement of arm 9 on arm 8 exerts a constrictive force on coil body 7 which tends to reduce the inside diameter thereof and thereby compresses it on the lead-in wire. The result is a clamping action which prevents, to a substantial degree, rotational or lateral movement of coil body 7 on the lead-in wire.

In the formation of connector 6, a Wire or ribbon must be used which has a degree of resiliency in order to exert the constrictive force mentioned above. I have found that tungsten wire having a fibrous structure is suitable. It is likely that other resilient refractory metals, such as tungsten-rhenium alloy, would be equally suitable.

Coil body 7 must be long enough to provide a satisfactory physical and electrical connection to lead-in wires 2 and 3 when arms 8 and 9 are engaged. However, since lead-in wires 2 and 3 can be connected to the base 10 at seals 4 prior to the mounting of the filament, only the internal ends of lead-in wires 2 and 3 are sometimes available for insertion into coil bodies 7. Therefore, when appropriate, coil body 7 must be short enough to slip fit over any bends in lead-in wires 2 and 3. For example, as shown in FIGURE 1, the coil bodies 7 which are assembled on lower lead-in wire 3 need negotiate no bends therein. However, upper lead-in wire 2 has a bend near its end, the purpose of which will be explained later, which must be negotiated by the coil bodies 7 mounted thereon. Therefore the bend on lead-in wire 2, although made as gradual as is practical, limits the length of the applicable coil bodies 7 to about the radius of curvature of the bend.

Coil supports 12, whose action is similar to that of connector 6, are used to stabilize long lead-in wire 2 against vibration and shock. This is especially important in those lamps where the longer lead-in Wire is at least several inches long and in supported only at the base. Coil support 12, as shown in FIGURE 3, comprises a coil body 13 and two protruding arms 14 and 15, again, as in filament connector 6, all made from a single length of refractory metal wire. However, arms 14 and 15 protrude in opposite directions from each other since their purpose is to press against the wall of envelope 1, the resultant pressure of which will exert the constrictive force on coil body 13. The requirements as to the resiliency of the wire, length of the coil body 13, relation of the diameter of the coil body 13 to that of the lead-in wire 2 and direction of the applied pressure are the same as those for connector 6, mentioned above. But, there being no need of electrical continuity between coil support 12 and leadin wire 2, the only improvement sought is the physical support of lead-in wire 2 by coil support 12 pressing against the inner wall of envelope 1.

In order to provide for this support, lead-in wire 2 can have two right angle bends near the top of envelope 1 so that two portions 16 and 17 of lead-in wire 2 are directly opposite each other, extend longitudinally with respect to envelope 1 and are adjacent to, but not touching, diametrically opposite parts of envelope 1. The space be tween portions 16 and 17 and the respective adjacent parts of envelope 1 is small enough to result in arms 14 and 15 pressing against envelope 1 when coil bodies 13 are inserted on portions 16 and 17 with arms 1.4 and 15 substantially orthogonal thereto. The disposition of coil sup ports 12 on portions 16 and 17 of lead-in wire 2 and the subsequent insertion of the mounted assembly comprising filaments 5, connectors 6, lead-in wires 2 and 3 and coil supports 12 into envelope 1 results, in effect, in two forces acting on portions 16 and 17. First, coil body 13 is constricted and compressed on its encircled portion of lead-in wire 2, as a result of envelope 1 pressing arms 14 and 15 in the direction of Winding of coil body 13. But, in addition, there is a radial force tending to press portions 16 and 17 toward each other. The result is an improved sup port for lead-in wire 2 against vibration and shock.

In a specific example of a lamp in accordance with this invention, the power rating of which was 5000 watts, envelope 1 was about 5 /5 inches long by 2 /2 inches diameter and was made of quartz. Seals 4 were similar to those disclosed in application Ser. No. 596,908, supra. Leadin wires 2 and 3 were made of 125 mil tungsten wire and were approximately 5 inches and 2 inches long, respectively, when measured from the base of the lamp to the furthest interior point. Lead-in wires 2 and 3 had several bends in order to place their respective filament mounting portions parallel to each other, about 3 inches apart and substantially diametrial with envelope 1. In addition, longer lead-in wire 2 had two right angle bends, as mentioned previously, which placed portions 16 and 17 about inch from their respective immediately adjacent sections of envelope 1.

Filament 5 was a coiled coil, about 1% inches long and Was made of 19 mil tungsten wire. Filament connector 6 was made of 28 mil tungsten wire and arms 8 and 9 had lengths of about /8 inch and inch, respectively. The end of arm 8 was bent into a curve, as mentioned previously, in a plane that was substantially orthogonal to the straight portion thereof. Arm 8 was connected to filament 5 by inserting the curved end into the terminal primary turns, the inside diameter of which was about 30 mils, for a span of about half a secondary turn. The book at the end of arm 9 was formed by two successive right angle bends of the wire, each having a length of about inch. Coil body 7 consisted of four touching turns which had been Wound on a mil mandrel. The normal springout of the resilient tungsten wire increased the inside diameter of coil body 7 to between about 118 to 126 mils. In the cases Where the inside diameter of coil body 7 was too small to permit a ready slip fit on the mil lead-in wire, a slight separation of arms 8 and 9 increased the coil diameter and permitted the slip fit thereon.

Coil support 12 was also made of 28 mil tungsten wire and coil body 13 thereof was wound identically to coil body 7, as described above. Arms 14 and 15 were about /8 inch long, which was sufiicient for their ends to press against circular envelope 1 when the whole mount assembly was inserted therein, as previously described.

Prior to sealing, the lamp was filled with nitrogen and bromine to about one atmosphere of pressure which, at normal operation, increased to a total pressure of about 4 atmospheres, with the lamp having a wall temperature of about 800 centigrade.

It is apparent that modifications and changes can be made within the spirit and scope of the instant invention, but it is my intention to be limited only by the appended claims.

I claim:

1. An incandesecent lamp having a filling including a halogen, comprising:

a tubular quartz envelope;

a lead-in wire extending within said envelope;

a filament disposed within said envelope;

a wire coil encircling said lead-in wire, said coil being substantially restricted in rotational and lateral movement about said lead-in wire by constricting means disposed at each end of said coil, said constricting means being an integral part of said coil, said filament being electrically connected to said lead-in wire through said constricting means; and

a second lead-in wire operatively connected to said filament.

2. The lamp of claim 1 wherein said constricting means comprises two arms protruding adjacently, one arm overlapping the other in compressive engagement with each other.

3. The lamp of claim 2 wherein said arms are unequal in length and the shorter arm has a hook at the end thereof for engaging the longer of said arms.

4. The lamp of claim 3 wherein the longer of said arms includes a curved segment at the end thereof, said segment being inserted into the terminal primary turns of said filament.

5. An incandescent lamp having a filling including a halogen, comprising:

a tubular quartz envelope;

a lead-in wire extending within said envelope; and

a Wire coil tightly encircling and stabilizing said lead-in wire, said coil being substantially restricted in rotational and lateral movement about said lead-in Wire by constricting means disposed at each end of said coil, said constricting means bearing against the inner surface of said envelope; whereby said lead-in wire is resiliently held in said envelope by the cooperative effect of said coil and means.

6. The lamp of claim 5 wherein said constricting means comprises two oppositely protrubing arms, each of said arms pressing against the inner surface of said envelope.

7. The lamp of claim 6 wherein a second wire coil, similar to said first wire coil, encircles a diametrically opposite section of said lead-in wire as is encircled by said first wire coil.

8. An incandescent lamp having a filling including a halogen comprising:

a tubular quartz envelope;

a filament disposed within said envelope;

a lead-in wire extending within said envelope;

a first and second wire coil encircling said lead-in wire; said wire coils being substantially restricted in rotational and lateral movement about said leadin wire by constricting means disposed at each end of each coil; said filament being electrically connected to said lead-in wire through said constricting means of said first coil;

said lead-in wire being stabilized and firmly held in place in said envelope by said constricting means of said second coil bearing against the inner surface of said envelope; and

a second lead-in wire operatively connected to said filament.

9. The lamp of claim 8 wherein said constricting means of said first coil comprises two arms protruding adjacently, one arm overlapping the other in compressive engagement with each other.

10. The lamp of claim 9 wherein said arms are unequal in length and the shorter arm has a hook at the end thereof for engaging the longer of said arms.

11. The lamp of claim 10 wherein the longer of said arms includes a curved segment at the end thereof, said segment being inserted into the terminal primary turns of said filament.

12. The lamp of claim 11 wherein said constricting means of said second coil comprises two oppositely protruding arms, each of said arms pressing against the inner surface of said envelope.

References Cited UNITED STATES PATENTS 923,797 6/ 1909 McNeill 313-274 2,462,325 2/ 1949 Leighton 313-333 3,403,280 9/1968 Cardwell 313-271 RAYMOND F. HOSSFELD, Primary Examiner U.S. Cl. X.R. 

